Carpet material



Patented Oct. 22, 1935 2,0l8,524 CARPET MATERIAL Albert W. Holmberg, Naugatuck, Coma, assignor,

by mesne assignments, to United States Rubber Company, New York, N. Y., a corporation of New Jersey No Drawing. Application September 1, 1933, Serial No. 687,817

4 Claims. (01. 91-68) This invention relates to carpet materials and more particularly to the sizing or coating on the backing of such carpet. materials.

It is conmion practice to coat or size carpet 5 backings by means of a to water solution of boiled starch. This boiled starch solution is generally applied to rug backings at a temperature of around 180 F. and on drying forms a stiff sizing which gives the rugthe desirable firmness, hardness and body. This sizing, however, cracks off during wear and is dissolved out when the rug is washed, leaving the carpet or rug in an I lmdesirably weakened and flabby condition.

Latex containing to 60% rubber solids is sometimes used to size. the backing and act as a stiffening material, andalso in some cases to lock the pile. Such a sizingmaterial, however, does not have the boardiness and rigidity of a starch sizing but does adhere satisfactorily to the backing during wear and washing of the carpet material. Mixtures of, boiled starch and latex in equal proportions have also been used as-sizing materials for rug backings .but as with the use of boiled starch alone, such a sizing cracks under 5 flexing and tends to dust off, the rubber material failing to hold the starch stiffening material to the fibers in the backing. 1

In preparing the sizing materials heretofore used, alone or admixed with latex, as before de- 9 scribed, the carbohydrate materials, such as starches, dextrines and the like, become peptized in the presence of water at-elevated temperatures, whether or not a preliminary swelling of the car bohydrate material has been allowed to take place 5 in water at room temperatm'e. The effect of starch granules in coldwater, for example, is limited to increasing the size thereof without disrupting the external sheath or covering of same. When the water swollen granule or thenormalun- 0 broken granule is subjected to elevated temperature for various periods of time, as in the prepara-- tion of boiled starch, the cell wall is actually rup-.

tured, and the amylo pectin is permitted to diffuse out into the aqueous phase and effect a colloidal dispersion of the granule content. Thus when such a colloidal dispersion of peptized starch, for example, is mixed with latex, the dispersed starch particles migrate throughout the aqueous phase along with the dispersed rubber globules and engulf and surround the same. As a result, when films of such a latex system are dehydrated, as in the drying of a rug sizing, the characteristics of the external starch phase predominate rather than the true flexible rubberthe starch but resultsin a cracking under flexdrying.

out sacrificing the rubber q 7 ant sizing, and with adv tag lower equip- 66 like characteristics of the latex globules which are situated beneath such external phase or coating. This relationship is reflected in increased stiffness, boardiness and rigidity by virtue of ing. In other words, such a compound has all of the properties of a starch size, both good and bad, with very few of the desirable properties associated with the increased flexibility of the rub-- ber, since the latter remains beneath thesurface w in the form of discrete, isolated, or separated rubber globules. The present invention relates to the production of carpet sizings having any desired degree of stiffness, boardiness and rigidity characteris- 15' I tic of a starch sizing and yet providing a method of locking the starch sizing to the backing so that it will not crack under flexing and furthermore impart in addition the desirable characteristics of increased flexibility, adhesion, water-proofing, and non-slip qualities associated with a rubber sizing.

According to the present invention it has been found possible to incorporate extremely large amounts of carbohydrate materials in a latex system for the production of sizing materials for carpets without impairing the flexibility and true rubber characteristics of the finished film after This is accomplished by controlling or eliminating peptization of the carbohydrate substances as a result of which we find the unpeptized, although water swollen, carbohydrate granule with the external sheath still unruptured, dispersed in rubber as the continuous phase in the dried film. with raw starch, for example, mixed 35 with latex. the rubber of the dried sizing will bevin a'continuous phase and the coating will possess all-of the desirable characteristics of such a rubber film as well as certain of the desirable properties characteristic of the starch granule 49 but free from the undesirable characteristics of cracking or breaking on flexing. Carbohydrate materials such as starches from wheat, corn, rice, tapioca, potato, arrowroot, etc., dextrines and the like, either in the form in which they are. normally obtained or as flour in the dry condition or swollen with cold water, are added directly to a latex system. .In no ,case is it considered advisable to introduce the factor of elevated temperature because of the danger of rupturing 50 the cell walls of the unpeptized carbohydratematerial. In addition, larger amounts of carbohydrate materials may be adde to the latex with es of the resultrubber in the sizing may take place during the drying operation or thereaftenif desired. Various natural laticessuch as normal latex or latex concentrated by a heat evaporation, or a chemical creaming process, or a mechanical creaming process, i. e., centrifuging, or a so-called vulcanized latex may be used.

The following examples of.a latex and raw starch sizing is included merely as an illustration of the invention:

v Parts Rubber as creamed latex 60% solids 100. Water in cream 66. Stabilizing agent 4. Water (to dissolve stabilizing agent) 36. Paste: I

Water 8.

Sulphur (precipitated) 2.

Zinc oxide '3.

KOH 0.5

Glue 0.1 Raw tapioca starch 170. Water (cold) 414. Accelerator 0.85 Antioxidant .33 Preservative .2

Such a composition will provide a desirable sizing for the carpet backing containing a major proportion of raw starch and a minor proportion of rubber.

It will be apparent to those skilled-in the art that any desired viscosity, thickness or apparent fluidity of the above system may be obtained by raising or lowering the amount of water used,

Preferably, the aqueous dispersion'contains vulcanizing ingredients 'so that vulcanization oi the with the corresponding effect on the total solids content. In addition, any of the well known methods of thickening latex systems or the addition of thickening agents may be used. An efficient method of securing increased viscosity effects in the above system is by the addition of a small amount of the tapioca starch in a peptized condition, as for example, by adding 5 to 30 parts 6 ing under flexing or dusting off of the carbohy- 15 drate material or of reversibility on'water during washing or shampooing of the rug for example. Such a coating has a rubbery appearance even when extremely high amounts of starch have been added to produce the desirable body to the backing, and yet the backing retains the desirable rubber properties of flexibility and nonslipping characteristics. The term carpet,- or carpet backing, as used in the description and claims is intended to include rugs, mats and similar fabrications, or the backings thereof, respectively.

With the above detailed disclosure of the invention, it is evident that numerous modifications will suggest themselves to those skilled in theart and it is not desired to limit the invention otherwise than as set forth in the appended claims.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. Acarpet'comprising awearing surface and a backing, said backing having a coating thereon comprising an admixture of unpeptized carbohydrate material and rubber.

2. A carpet comprising a wearing surface and a backing, said backing having a coating thereon comprising an admixture of raw starch and rub- 40 her.

3. A carpet comprising a wearing surface and a backing, saidbacking having a coating thereon comprising an admixture of raw starch andthe directly deposited solids of an aqueous dispersion of rubber.

4. A carpet comprising a wearing surface-and a backing thereon comprising an admixture of a 'major proportion of raw starch and a minor proportion of the directly deposited solids of an aqueous dispersionof rubber.

ALBERT W. HQLMBERG. 

